Contemporary asymmetric synthesis is a widely used method for stereocontrolled creation of stereogenic centers in organic molecules. During recent years, this approach to organic synthesis greatly contributed to progress in the directed introduction of various functionalities and in the highly controlled formation of new centers of chirality. These processes still remain the basic problems in the total synthesis of natural products or medicinals. Preparation of the latter in optically pure form by application of chiral starting materials is very advantageous, enabling precise planning and efficient realization of synthetic pathways.
Many monosaccharides and their readily available derivatives are versatile substrates for the synthesis of optically active target molecules. For example, 2,3,0-isopropylideneglyceraldehyde (1) has been widely used as one of the chosen substrates; it is characterized by availability of both enantiomers from natural sources, and by pronounced versatility due to the presence of the aldehyde and protected diol functionality in the same small molecule.
Another building block for various bioactive compounds is glycidaldehyde (2). ##STR1##
Although compounds (1) and (2) have enjoyed considerable success as substrates in synthesis routes to other substances, they suffer from some severe disadvantages. Despite the versatility of optically active glycidaldehyde (2), its high volatility and high genotoxicity, in addition to its high solubility in aqueous solutions, have restricted its wide use. Additionally, both chiral building blocks (1) and (2) are unstable and no commercial supply of these compounds exists so far.
It is readily apparent that there is a need for compounds like (1) and (2) which can be stored for extended periods of time and are not hazardous.